Objective:
The objective of this research is to develop technologies for manipulating livestock embryos for the purpose of creating genetically modified livestock. One sample project that will be conducted is the genetic modification of genes involved in reducing the boar taint phenotype in pigs. Boar taint is an offensive odor/taste detectable in pork products derived from sexually mature non-castrated male pigs. It is caused by two compounds accumulating in fat deposits; androstenone, which is derived from sex steroids, and skatole, a metabolite of tryptophan which is produced by bacteria in the hind gut and is stored in pig fat. In a collaborative project, one of the Cooperators has identified two genes involved in the formation of androstenone and investigated the utility of novel single nucleotide polymorphisms (SNPs) in these genes to reduce boar taint via site directed mutagenesis and an in vitro steroid assay predictive of in vivo production of androstenone. The Cooperator believes this project has identified candidate SNPs which will result in normally sexual boars with very low potential for boar taint. A goal of this NFCA is to introduce these point mutations into the genome to create genetically modified pigs in such a way as to introduce no foreign DNA while alleviating the Boar Taint phenotype.

Approach:
All Cooperators are interested in alleviating the Boar Taint phenotype using Transcription Activator-Like Effector Nucleases (TALENs) genome editing to introduce candidate SNPs into these genes by co-injecting TALEN mRNA along with template DNA carrying the point mutations into porcine zygotes, reintroduce these embryos into recipient females, and bring the piglets to term. The resulting genome edited progeny will not carry any foreign DNA and are thus much more likely to be approved for human consumption by the Food and Drug Administration and other regulatory agencies. If successful this technology would provide a significant animal welfare benefit in that it would help obviate the need to castrate male piglets destined for meat production, as well as offering producers the benefit of more efficient production of lean pork.